Low temperature synthesis of cubic CdSe, HgSe and (CdHg)Se thin films and their characterization

A low temperature synthesis of CdSe, HgSe and Cd_0.5Hg_0.5Se alloy thin films in cubic modification under similar set of conditions is presented. The method is based on chemical reaction of complexed cadmium sulphate, mercuric nitrate or mixtures of both with sodium selenosulphate in aqueous ammonical medium at 5 °C. The films were characterized by using XRD, Optical absorption, Electrical measurements AAS and EDAX techniques. The films were found to be uniform, well adherent, dark red, nearly stoichiometric and polycrystalline in cubic form without trace of any hexagonallity. The growth of film was found to occurs by ion by ion by ion nucleation. CdSe, HgSe and (CdHg)Se films showed optical band gaps at 1.75 eV, 0.81 eV and 1.34 eV respectively. The electrical conductivity of (CdHg)Se alloy was found to be of the order of 10⁻² (Θcm)⁻¹. The rate of increase of conductivity with temperature was found to reduce with the inclusion of mercury. Thermoelectric study indicated the presence of n-type conduction mechanism for all the films. Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.